> Without checking the implementation, how would you know how the input-data should be formatted? How does OOP solve this problem? Either way, you need to chec

> Without checking the implementation, how would you know how the input-data should be formatted? How does OOP solve this problem? Either way, you need to check the type signature of the function. If your IDE does that for you, that's great, but it's not an inherent difference between OOP and FP.